JP3221463B2 - Polyacetal resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyacetal resin composition having improved weather resistance and thermal stability. More specifically, the present invention relates to a polyacetal resin, which comprises an antioxidant 1,6-bis [3- (3,5-di-t-butyl-4
-Hydroxyphenyl) propionamide] hexane, light stabilizer bis [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate, and UV absorber Melt-mixing weather (light) resistance,
Also, the present invention relates to a polyacetal resin composition having improved thermal stability, particularly thermal stability during molding.

[0002] The polyacetal resin of the present invention can be used for weathering (light) without impairing the inherent properties of the polyacetal resin.
Highly improved properties and thermal stability, and excellent mechanical properties, so it is used for a long time exposed to sunlight, room lights, etc. It can be awarded as a component, for example, a car out-handle, a wheel cover, a front fender, a component of an electric device, or a material such as a building material or a greenhouse packer.

[0003]

2. Description of the Related Art Polyacetal resin compositions are required to have physical properties such as friction and wear resistance, fatigue resistance, heat resistance and electrical properties, and chemical properties such as chemical resistance and water resistance. Because of its superiority, it has been awarded as a part in the fields of electric / electronics and architecture, as well as in the automobile industry and sundries.

[0004] It is known that polyacetal resin, which is a raw material of the polyacetal resin composition, has poor thermal stability and causes a thermal decomposition reaction in a melt-kneading operation performed at the time of molding. Therefore, various antioxidants, heat stabilizers, and the like are added in order to prevent a thermal decomposition reaction during the molding process. In addition, when the polyacetal resin is exposed to sunlight, room light, etc. for a long time, in particular, when further exposed to the weather, cracks first occur on the surface, and as the progress proceeds, the gloss is lost and the appearance deteriorates, It is known that, together with the deterioration of the appearance, the mechanical properties are significantly reduced and the practicality and practical value are lost. In order to prevent the deterioration due to light such as sunlight, a light stabilizer and an ultraviolet absorber are added.

[0005] The heat resistance can be improved by adding an antioxidant or a heat stabilizer to a polymer material, ie, a synthetic resin, but sometimes the added antioxidant acts as a photosensitizer. A photosensitizing effect is caused to deteriorate weather resistance. In addition, as a method for improving the weather resistance of the polymer material, a method of adding a light stabilizer, for example, a hindered amine type, a method of adding an ultraviolet absorber, for example, a benzotriazole type, a benzophenone type, etc., a light stabilizer and ultraviolet absorption Although there is a method of using a combination of agents, the weather (light) resistance is improved by adding a light stabilizer or an ultraviolet absorber alone without using an antioxidant, or by using a light stabilizer and an ultraviolet absorber in combination, There is no effect of improving heat resistance. In particular, in the case of polyacetal resin, which has poor thermal stability among polymer materials, without an antioxidant, the thermal stability during molding processing is extremely poor, and silver on the product surface, around the cavity of the mold and around the core, Mold deposits are likely to occur.

However, in general, even if an antioxidant and a light stabilizer or an ultraviolet absorber are added to a polymer material, particularly a polyacetal resin, depending on the selection, in other words, depending on the combination, the antagonism may occur. Occurs, and the effect, that is, the effect of improving the weather (light) resistance, cannot be obtained, and the intended purpose cannot be often achieved. Therefore, in particular, the effects of the antioxidant, the light stabilizer, the ultraviolet absorber, and the like to be added to and blended with the polyacetal resin must be selected and determined by trial and error by confirming the effects thereof experimentally.

It has been known that the addition of a hindered amine-based light stabilizer alone or in combination with an ultraviolet absorber has a considerable effect on improving the weather (light) resistance of a polyacetal resin. It is not always satisfactory depending on the purpose of use. For example, in the case of using a high molecular weight hindered amine-based light stabilizer, its migration property is poor. Therefore, in order to obtain sufficient weather resistance (light), a very large amount must be added. It is not practical because it causes problems such as reduction in cost and increase in cost. In contrast, the use of low molecular weight hindered amine light stabilizers causes problems such as poor product appearance due to bleed-out of additives, despite the amount of additives,
Further, since the amount of the additive volatilized during molding is large, increasing the amount of the additive does not lead to improvement in weather resistance.

[0008]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies on polyacetal resin compositions in order to solve the above-mentioned problems. As a result, the polyacetal resin was identified as a specific hindered phenol compound. By adding and blending a hindered amine compound and an ultraviolet absorber such as benzotriazole, and uniformly kneading and mixing, the excellent friction and wear resistance and fatigue resistance of the inherent polyacetal resin With the knowledge that it is possible to obtain a polyacetal resin composition having excellent heat stability during molding and weather resistance (light) without impairing chemical resistance and electrical properties, Further, experiments for confirming technical improvement and reproducibility were performed, and the present invention was completed.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a polyacetal resin, which comprises an antioxidant 1,6-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide] hexane and a photo-oxidant. Stabilizer bis [N-methyl-2,2,6,6-tetramethyl
-4-piperidinyl] sebacate and an ultraviolet absorber are added and blended and uniformly kneaded and mixed. The present invention relates to a polyacetal resin composition having improved weather resistance (light) and thermal stability. More specifically, the invention of the present application is based on 100 parts by weight of the polyacetal resin (A),
Bis [3- (3,5-di-t-butyl-4-hydroxyphenyl)
Propionamide] hexane (B) 0.01-0.50 parts by weight and bis [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate (C) 0.10-1.0 parts by weight, and an ultraviolet absorber ( D) 0.1 to 1.0 parts by weight of a polyacetal resin composition having improved weather resistance and heat stability obtained by uniformly kneading and mixing the resulting mixture.

[0010] In the present invention, the polyacetal resin
(A) means a polyacetal (polyoxymethylene) and a polyacetal copolymer which are already generally commercially available. More specifically, for example, formaldehyde or its trimer (trioxane),
And an oxymethylene homopolymer substantially consisting of an oxymethylene unit structure and / or formaldehyde or its trimer (trioxane) produced from its tetramer (tetraoxane), and its tetramer (Tetraoxane) and 2 carbon atoms such as ethylene oxide, epichlorohydrin, 1,3-dioxolan, 1,3,5-trioxepane, formal of glycol, formal of diglycol, and formal of diglycol
Oxymethylene copolymers or oxymethylene homopolymers containing 0.1 to 20% by weight of an oxyalkylene unit structure produced from a cyclic ether of
Alternatively, a block structure other than an oxymethylene unit structure having an oxymethylene copolymer as a main structure, or an oxymethylene block copolymer having a terminal structure, or an oxymethylene graft polymer, or a known oxymethylene crosslinked polymer having a crosslinked structure. Means that.

The antioxidant (B) added / blended in the present invention has the following general formula:

[0012]

Embedded image

Wherein R1 and R2 each represent a hydrogen atom, a linear lower alkyl group, or a branched lower alkyl group. m, n
Means an integer. 1, ω- screw [ω'-
(3,5-di-substituted-4-hydroxyphenyl) alkylcarbonamido] alkanes wherein R ₁ and R ₂ are t-butyl groups, m is 2 and n is 6 (3- (3,5-di
-t-butyl-4-hydroxyphenyl) propionamido] hexane (B), that is, a specific hindered phenol compound.

Light stabilizer added / blended in the present invention
(C) is the following formula

[0015]

Embedded image Bis [N-methyl-2,2,6,6-tetramethyl-4-
Piperidinyl] sebacate (C), a specific hindered amine compound.

In the present invention, the antioxidant is limited to 1,6-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamido] hexane because of the synthesis of the compound. , And the availability and restrictions, and not based on the effect as an antioxidant. In other words, the selection and limitation are based on the fact that the effect of the compound as an antioxidant has not been experimentally confirmed. Therefore, in the near future, 1,6-bis [3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionamide
The compound other than hexane, that is, several kinds of compounds represented by the above general formula were synthesized and subjected to experiments and evaluation tests, and it was confirmed that they had the same effect as the experimental fact. Presumed and expected.

In the present invention, the antioxidant is 1,6
-Bis [3- (3,5-di-t-butyl-4-hydroxyphenyl)
[Propionamido] hexane is limited to hexane because the effect of improving weather resistance (light) due to antagonism with a light stabilizer or an ultraviolet absorber used in combination with or added to the compound is substantially eliminated. Based on results.

The antagonism between the antioxidant and the light stabilizer and the ultraviolet absorber in the polymer material, in particular, the polyacetal resin composition, in other words, the desired weather (light) resistance and heat stability can be obtained. In order to clarify the reason and mechanism of action, we must further wait for detailed research results in the future. From the experimental results obtained so far, dare to infer that the operation of adding and blending a hindered phenolic antioxidant and an ultraviolet absorber and / or a light stabilizer to the polyacetal resin, more specifically, melting It can be said that this is because the ultraviolet absorber and / or the light stabilizer and the antioxidant undergo a chemical reaction and are consumed during kneading.

The antioxidant of the present invention exhibits an excellent effect of improving weather (light) resistance under the conditions of melt-kneading under the condition that the UV absorber and / or UV absorber is added and / or added.
It is considered that it hardly reacts with the light stabilizer, in other words, it hardly reacts and is hardly consumed, that is, it has very little mutual antagonism. Further, the antioxidant of the present invention, that is, 1,6-bis [3- (3,5-di-t-butyl-4-
(Hydroxyphenyl) propionamido) hexane is
The reason that it is difficult to react with the UV absorber and / or the light stabilizer added / added is that the effect of the active hydrogen of the amide bond in the molecular structure, more specifically, the active hydrogen of the amide bond is It is thought that the carbon radical generated on the phenol ring [position 4] is captured and annihilated / deactivated.

Further, in the present invention, the light stabilizer is bis [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl].
The reason for being limited to sebacate is that the addition of the compound has a large effect of improving the weather resistance (light) of the polyacetal resin composition, and the appearance of the product due to the volatilization of the additive during molding and the bleed out of the additive. It is based on experimental results that no problems such as defects occur.

The reason why the light stabilizer of the present invention is excellent is that 1,6-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamido] hexane as an antioxidant is consumed. In addition to the difficulty, it is thought to be due to its appropriate molecular weight. For example, when a hindered amine light stabilizer having a higher molecular weight than bis [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate is used, its migration property is poor, so that sufficient weather resistance (light) is required. In order to obtain the properties, very large amounts must be added. In contrast, bis [N-methyl-2,
[2,6,6-tetramethyl-4-piperidinyl] The use of hindered amine light stabilizers having a smaller molecular weight than sebacate, despite the amount of addition, may cause problems such as poor product appearance due to additive bleed-out. Is generated, and the amount of the additive volatilized during molding is large. Therefore, even if the added amount is increased, the weather resistance is not improved.

In the present invention, the ultraviolet absorber (D) is one selected from the group consisting of benzotriazole compounds, benzophenone compounds, aromatic benzoate compounds, cyanoacrylate compounds, and oxalic anilide compounds. The above compounds are meant. More specifically, for example, 2- (2'-hydroxy-5'-methyl-phenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'
-Di-t-butylphenyl) benzotriazole, 2- (2'-
Hydroxy-3 ', 5'-di-isoamylphenyl) benzotriazole, 2- [2'-hydroxy-3', 5'-bis- (α,
α-dimethylbenzyl) phenyl] benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-
Octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-oxybenzylbenzophenone , 2-hydroxy-4-methoxy-5-sulfobenzophenone, pt-butylphenyl salicylate, p-
Octylphenyl salicylate, 2-ethylhexyl-2-
Cyano-3,3'-diphenyl acrylate, ethyl-2-cyano-3,3'-diphenyl acrylate, N- (2-ethoxy-5-t
-Butylphenyl) oxalic acid diamide, N- (2-ethylphenyl) -N '-(2-ethoxyphenyl) oxalic acid diamide, and the like.

In practicing the present invention, when the intended polyacetal resin composition is used for general applications, it is not particularly necessary to select a polyacetal resin of a special quality. The purpose can be sufficiently achieved by appropriately selecting from among polyacetal resins commercially available in the form of flakes, flakes, or pellets in consideration of their uses.

In the present invention, 1,6-bis [3- (3,5-
The amount of di-t-butyl-4-hydroxyphenyl) propionamido] hexane, that is, the specific hindered phenol compound (B), is 0.01 to 0.50 parts by weight based on 100 parts by weight of the polyacetal resin. 1,6-bis [3- (3,5-
When the amount of [di-t-butyl-4-hydroxyphenyl) propionamido] hexane (B) is less than 0.01 part by weight, sufficient heat resistance cannot be obtained. Conversely, the amount of the specific hindered phenol compound (B) is 0.
If the amount is more than 50 parts by weight, weather (light) resistance is reduced, and it is economically disadvantageous. Usually, it is generally preferable to select about 0.20 to 0.35 parts by weight.

In carrying out the present invention, bis [N-methyl
-2,2,6,6-tetramethyl-4-piperidinyl] sebacate, that is, the specific hindered amine compound (C) is used in an amount of 0.10 to 100 parts by weight of the polyacetal resin.
1.0 part by weight, more preferably 0.10 to 0.50 part by weight. The compounding amount of the specific hindered amine compound (C) is
If the amount is less than 0.10 part by weight, the synergistic effect with the ultraviolet absorber cannot be sufficiently exerted.On the other hand, if the amount of the specific hindered amine compound (C) is more than 1.0 part by weight, the molded article is not obtained. However, it is not preferable because it causes a decrease in the mechanical properties.

When carrying out the present invention, an ultraviolet absorber
The amount of (D) is 0.1 to 1.0 part by weight based on 100 parts by weight of the polyacetal resin. If the amount of the ultraviolet absorbent (D) is less than 0.1 part by weight, sufficient weather (light) resistance cannot be obtained. Conversely, if the blending amount of the ultraviolet absorber (D) is more than 1.0 part by weight, the coloring of the molded product and the mechanical properties (physical properties) deteriorate, which is economically disadvantageous. .

When carrying out the present invention, the polyacetal resin composition of the present invention may further contain carbon black, a known filler, a pigment, a surfactant,
One or more kinds of antistatic agents, lubricants, nucleating agents and the like can be appropriately added as long as the effects of the present invention are not impaired.

In practicing the present invention, the polyacetal resin composition of the present invention may be mixed with a generally known melt-kneading apparatus, more specifically, a single-screw or twin-screw extruder or kneader, and a pelletizer. Can be easily manufactured. To explain this more specifically,
The polyacetal resin composition of the present invention can be prepared according to a generally known method, for example, by adding a predetermined amount of 1,6-bis [3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionamido] hexane (B) and bis [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate (C) and ultraviolet absorber (D) is added and blended, uniformly mixed using a super mixer or the like, melt-kneaded using a twin-screw extruder or the like, and subsequently pelletized.

The polyacetal composition of the present invention obtained here has excellent thermal stability during injection molding, and is therefore generally known in the art, that is, injection molding, extrusion molding, compression molding, and blow molding. It can be easily formed by a molding method, a vacuum molding method, a foam molding method, or the like.

Hereinafter, the present invention will be described specifically and in detail with reference to examples and comparative examples, but the following examples are for the purpose of specifically explaining the present invention. It is not intended to limit the embodiments or the scope of the invention.

[0031]

【Example】

Example 1 100 parts by weight of a polyacetal resin [Mitsubishi Gas Chemical, Iupital, melt index MI 10 g / 10 min], 1,6-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide] Hexane 0.10 parts by weight, bis [N-methyl
-2,2,6,6-Tetramethyl-4-piperidinyl] sebacate
0.35 parts by weight, 2- [2'-hydroxy-3 ', 5'-bis (α,
α-Dimethylbenzyl) phenyl] benzotriazole
0.35 parts by weight, melamine 0.20 parts by weight, and calcium stearate 0.05 parts by weight were weighed and uniformly mixed using a super mixer (manufactured by Kawada Seisakusho), and then, according to a conventional method, a twin screw extruder (manufactured by Ikegai Iron Works, PCM) -30, screw diameter 30mm], melt-kneading under the conditions of screw rotation speed 50rpm, cylinder set temperature 220 ° C,
Pelletized. The pellets obtained here are heated at a temperature of 80 ° C.
After drying for 4 hours using a hot air dryer, a strip type test specimen [for weather (light) resistance test, size, using an injection molding machine [Sumitomo Heavy Industries, SG125 type, theoretical injection capacity 163 ml]]
3.2 × 12.7 × 63.6mm] [Operation conditions: mold temperature 80
℃, cylinder set temperature 200 ℃, injection pressure 800kg / cm ² ,
Molding cycle 40 seconds]. Subsequently, change the cylinder set temperature to 235 ° C and extend for 5 minutes each time one shot is molded [Molding cycle: 5 minutes, 10 minutes, 15 minutes, 20 minutes, ...
・] Meanwhile, the injection molding operation was repeated until silver was generated on the surface of the strip-shaped test piece, and a retention heat resistance test was performed. As a result, generation of silver was observed in a molding cycle of 30 minutes. The strip-shaped test piece obtained here was attached to a predetermined position of a weather meter (manufactured by Suga Test Instruments, WBL-SUN-HCH type), and the method A was used (black panel temperature).
The treatment was carried out under the conditions of 63 ° C., no rain spray) and Method B (black panel temperature 83 ° C., no rain spray). In the case of Method A, processing time for strip-shaped test specimens from testing machine 1
When taken out every 00 hours and observed for cracks and bleed-out, cracks were observed at 900 hours [referred to as crack occurrence time]. In the case of Method B, a strip-shaped test piece was processed from the testing machine for 5 hours.
The sample was taken out every 0 hours and observed for cracks and bleed-out. Cracks were observed at 650 hours. In addition, A indicates that the bleed-out of the additive was not present on the surface of the test piece, B indicates that the bleed-out was slightly observed, and C indicates that the bleed-out was observed.
[See Table 1]. The pellets obtained here were dried using a hot air dryer at a temperature of 80 ° C. for 20 hours,
1500 shot molding using a drop mold [Injection molding machine: manufactured by Sumitomo Heavy Industries, MINIMAT8 / 7A mold, mold clamping force 7tf. Operating conditions: mold temperature 35 ° C, cylinder set temperature 230 ° C, injection pressure 7
00 kg / cm ² , molding cycle 10 seconds], and then a mold deposit was observed. When the degree of the mold deposit was slightly adhered to the contour of the cavity, ○ was shown, and when the entire area was completely white around the cavity, * was given (see Table 1). Examples 5 and 6 and Comparative Examples 12 and 13
Regarding Examples 19 and 20, the residual amount of the light stabilizer in the test piece was measured using the strip-shaped test piece obtained as described above. The quantification was performed by extracting chloroform for 10 hours with respect to 10 g of the crushed product of each sample, measuring the extract to 5 ml, and then performing the calibration curve method using a GC chromatogram. Table 5 shows the results.

Example 2 In Example 1, 1,6-bis [3- (3,5-di-t-butyl-4
-Hydroxyphenyl) propionamide] Hexane was treated in the same manner as in Example 1 except that the amount of hexane was changed from 0.10 part by weight to 0.50 part by weight, and the results shown in Table 1 were obtained.

Examples 3 to 7 In Example 1, 1,6-bis [3- (3,5-di-t-butyl-4
-Hydroxyphenyl) propionamide] hexane was changed from 0.10 part by weight to 0.30 part by weight, and bis [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate was 0.35 part by weight. Except that 0.35 parts by weight of 2- [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] benzotriazole was changed to the respective parts by weight shown in Table 1. By performing the same treatment as in Example 1, the results shown in Table 1 were obtained.

Example 8 In Example 1, 1,6-bis [3- (3,5-di-t-butyl-4
-Hydroxyphenyl) propionamido] hexane from 0.30 parts by weight to 0.30 parts by weight, 0.35 parts by weight of 2- [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] benzotriazole Instead of part 2
Except that 0.35 parts by weight of-(2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole was used, all treatments were carried out in the same manner as in Example 1 to obtain the results shown in Table 1. .

Comparative Examples 1 to 6 In Example 1, 1,6-bis [3- (3,5-di-t-butyl-4
-Hydroxyphenyl) propionamido] Hexane and other additives were changed as shown in Table 2 except that all treatments were carried out in the same manner as in Example 1 and the results shown in Table 2 were obtained. I got

Comparative Examples 7 to 11 In Example 1, 1,6-bis [3- (3,5-di-t-butyl-4
-Hydroxyphenyl) propionamide] hexane
All treatments were carried out in the same manner as in Example 1 except that each of the various hindered phenolic antioxidants shown in Table 3 was used instead of 0.10 parts by weight, and the results shown in Table 3 were obtained. Was.

Comparative Examples 12 to 19 In Example 1, various hindered amines having the compounding amounts shown in Table 4 were used in place of bis [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate. Except for using the light stabilizer, all treatments were performed in the same manner as in Example 1 to obtain the results shown in Table 4.

[0038]

As described above, the polyacetal resin composition of the present invention comprises 1,6-bis [3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionamido] hexane (B) and bis [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate (C) or UV-absorbing ( D) is added and blended and uniformly melt-kneaded, and has extremely excellent moldability, thermal stability, and weather (light) resistance, and excellent weather (light) resistance It can be suitably used as a material for various molded products requiring, for example, parts for electric equipment such as outdoor handles, wheel covers and front fenders of automobiles, and building materials.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

Continuation of the front page (72) Inventor Toshiaki Okazono 5-6-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Examiner, Plastics Center, Mitsubishi Gas Chemical Co., Ltd. Satoshi Morikawa (56) References JP-A-63-193950 (JP, A) JP-A-52-51443 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 59/00-59/04

Claims (2)

(57) [Claims] 1. An antioxidant 1,6-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide] based on 100 parts by weight of a polyacetal resin (A). Hexane 0.01 to 0.50 parts by weight and (C) light stabilizer bis [N-methyl
-2,2,6,6-Tetramethyl-4-piperidinyl] sebacate
0.10 to 1.0 part by weight and (D) 0.10 to 1.0 part by weight of an ultraviolet absorber are added and blended and uniformly melt-kneaded to improve the weather (light) resistance and heat stability of the polyacetal resin composition. object. 2. The ultraviolet absorber is one or more compounds selected from a benzotriazole compound, a benzophenone compound, an aromatic benzoate compound, a cyanoacrylate compound, and an oxalic anilide compound. The polyacetal resin composition according to the above.